Dibasic Calcium Phosphate Dihydrate Excipient | Uses, Suppliers, and Specifications
Dibasic Calcium Phosphate Dihydrate is an inorganic mineral compound and pharmaceutical excipient that contains Calcium ions (Ca2+) together with phosphate anions in a 1:1 molar ratio (chemical formula CaHPO4.2H2O). It is supplied as a white, odourless, tasteless powder or crystalline solid and occurs as triclinic crystals.
Synonyms and Trade Names: Dibasic Calcium Phosphate Hydrate; Calcium Hydrogen Phosphate; Calcium Hydrogen Phosphate Dihydrate; Calcium Hydrogen Orthophosphate dihydrate; Calcium Monohydrogen Phosphate Dihydrate; Di-Cafos; Dicalcium Orthophosphate; DI-TAB; E341; Emcompress
Uses and Applications: Tablet and Capsule Diluent and Source of Calcium
Dibasic calcium phosphate dihydrate is an inorganic mineral and pharmaceutical excipient that is chemically composed of Calcium ions (Ca2+) and phosphate anions in a 1:1 molar ratio. It is also known as Calcium hydrogen phosphate dihydrate, Calcium hydrogen orthophosphate dihydrate, Calcium monohydrogen phosphate dihydrate, Dicalcium orthophosphate, DCP and DCPD.
Dibasic calcium phosphate belongs to a family of eleven mineral compounds that are collectively known as Calcium phosphate. They find important applications across the medical, geology, construction, and dentistry sectors. Depending on the methods of production, the materials obtained differ in function, composition, structure, physical properties and applications.
In the pharmaceutical field, the three most important minerals from this family are Dibasic calcium phosphate anhydrous, Dibasic calcium phosphate dihydrate, and Tricalcium phosphate, which are used as diluents and fillers in solid dosage development.
Dibasic calcium phosphate dihydrate has the empirical formula CaHPO4.2H2O, and therefore exists as the dihydrate. The “di” prefix in the common name arises because the formation of the HPO42– anion involves the removal of two protons from phosphoric acid, H3PO4.
Dibasic calcium phosphate dihydrate is a white, odourless, tasteless powder or crystalline solid, and occurs as monoclinic crystals.
Chemical Structure & Identifiers
|Chemical Name||Calcium hydrogen phosphate dihydrate|
|CAS Registry Number||[7789-77-7]|
Dibasic calcium phosphate dihydrate is an approved pharmaceutical excipient and an authorised food additive in Europe. It is currently listed in the USP-NF, Ph.Eur and J.P. It is also GRAS listed and is included in the FDA Inactive Ingredients Database (covering oral capsules and tablets). Dibasic calcium phosphate dihydrate finds wide use in oral pharmaceutical products, food products, and toothpastes owing to its acceptability as a relatively nontoxic and non-irritant material.
|Appearance||White powder or crystalline solid|
|pH (20% slurry)||7.4|
|Angle of repose||28.30|
|Bulk density||0.915 g/ml|
|Tapped density||1.17 g/ml|
|True density||2.389 gml|
|Flowability .||9 – 30 g/s (dependent on grade)|
Dehydrates below 1000C
|Moisture content||Typically < 5%. Dibasic turn phosphate dihvdrate contains two molecules of water of crystallization, which can he lost at temperatures well below 1000C,|
|Particle size distribution||Varies depending on grade. Coarse grades typically 200 µm while fine grades are ~ 10 µm.|
|Solubility||Practically insoluble in ethanol, ether, and water; soluble in dilute acids.|
|Specific surface area||0.44 – 0.46 m2/g|
|Official name||Dibasic Calcium Phosphate Dihydrate||Calcium Hydrogen Phosphate Dihydrate||Dibasic Calcium Phosphate Hydrate|
|Loss on ignition||24.5 -26.5%||24.5 -26.5%||n/a|
|Loss of drying||n/a||n/a||19.5 -22.0%|
|Acid-insoluble substances||≤ 0.2%||≤ 0.2%||≤ 0.05%|
|Heavy metals||≤ 0.003%||≤ 40 ppm||≤ 31 ppm|
|Chloride||≤ 0.25%||≤ 0.25%||≤ 0.248%|
|Fluoride||≤ 0.005%||≤ 100 ppm||–|
|Sulfate||≤ 0.5%||≤ 0.5%||≤ 0.160%|
|Arsenic||≤ 3µg/g||≤ 10 ppm||≤ 2 ppm|
|Iron||n/a||≤ 400 ppm||n/a|
|Assay||98.0 -105.0%||98.0 -105.0%||≥ 98.0%|
Key: n/a Specification is not listed
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Applications in Pharmaceutical Formulations or Technology
Dibasic calcium phosphate dihydrate is primarily used as a tablet filler and diluent. It is also used as a source of calcium and phosphorus in nutritional supplements. It is one of the more widely used excipients, not only in pharmaceutical products but also in nutraceuticals and also in toothpastes owing to its abrasiveness.
In the pharmaceutical formulations, Dibasic calcium phosphate dehydrate is selected because of its excellent compactability and flow properties. The predominant deformation mechanism of coarse-grades is brittle fracture which significantly reduces strain-rate sensitivity and the tendency for tablets to laminate. This is highly advantageous during formulation scale-up in new product development which is less arduous. The only downside is that dibasic calcium phosphate dihydrate is abrasive, which severely reduces tooling life. Thereofore, high levels of lubricants are required in formulations (usually higher than 1% w/w for Magnesium stearate or Sodium stearyl fumarate).
Commercial grades of Dibasic calcium phosphate dihydrate are available in the form of a milled grade typically reserved for use in wet-granulation or roller-compaction, and a coarse grade meant for direct-compression applications.
Dibasic calcium phosphate dihydrate does not absorb moisture from the environment and remains stable at ambient conditions. However, if the material is subjected to particular conditions (high temperature and humidity), it can lose its water of crystallization. This phenomenon can have implications for high-temperature processes (packaging and aqueous film coating) or most moisture-sensitive actives.
Safety and Precautions
Dibasic calcium phosphate dihydrate is widely used in oral pharmaceutical products, food products, and toothpastes owing to its acceptability as a relatively nontoxic and non-irritant material.
Stability and Storage Conditions
Dibasic calcium phosphate dihydrate is a nonhygroscopic, relatively stable material. However, when incorrectly stored or processed, it can lose its water of crystallization, which can impact the stability of the excipient and subsequent processing of dosage forms. Therefore, the bulk material should be correctly stored (in a well-closed container in a cool, dry place away from direct heat or moisture).
When handling Dibasic calcium phosphate dihydrate, workers should observe required precautions appropriate to the circumstances and quantity of material being processed. As the milled grades can generate dust, the use of a respirator or dust mask is recommended.
Sustainability and Environmental Impact
Dibasic calcium phosphate is a naturally-occurring mineral although it may be obtained obtained synthetically using widely available non-critical resources. Being inert and non-toxic, it is considered safe for the environment, with minimal long-term impact on ecology or marine life. Dibasic calcium phosphate achieved a total score of 78/100 by the Excipients Forum Sustainable™ Chemistry.
Manufacturers & Suppliers
Additional Resources (Downloads)
References and Literature Used
 Z.T. Chowhan, The effect of low- and high-humidity ageing on the hardness, disintegration time and dissolution rate of dibasic calcium phosphate-based tablets, The Journal of Pharmacy and Pharmacology, 32 (1980) 10-14.
 M. Landin, R. Martinez-Pacheco, J.L. Gómez-Amoza, C. Souto, A. Concheiro, R.C. Rowe, Dicalcium phosphate dihydrate for direct compression: Characterization and intermanufacturer variability, International Journal of Pharmaceutics, 109 (1994) 1-8.
 N. Tarlier, I. Soulairol, B. Bataille, G. Baylac, P. Ravel, I. Nofrerias, P. Lefevre, T. Sharkawi, Compaction behavior and deformation mechanism of directly compressible textured mannitol in a rotary tablet press simulator, Int J Pharm, 495 (2015) 410-419.
 G.K. Reynolds, J.I. Campbell, R.J. Roberts, A compressibility based model for predicting the tensile strength of directly compressed pharmaceutical powder mixtures, International Journal of Pharmaceutics, 531 (2017) 215-224.
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